In the mid nineteen sixties, Quad could do no wrong. Its recently launched ESL-57 electrostatic loudspeaker was ground-breaking, and considered one of the very best designs in the world. Its Quad II valve power amplifiers were of excellent quality too, and had won a great many friends. This made it all the more problematic for company founder Peter Walker, when the time came to replace them…
The successor would of course have to be solid-state. Quad considered itself to be a cutting-edge company, basking in the “white heat of the technological revolution”, as the then Prime Minister Harold Wilson put it. There was no way that the company’s new amplifier would be another tube design. The problem was that transistor technology was in its infancy though, and many amplifiers suffered from thermal tracking problems, making for sonic and reliability problems.
Launched in 1967, the new Quad 303 power amplifier featured an innovative ’triples’ output transistor configuration which gave effective control of the output current. Since the voltage was also controlled, they could only operate within their ratings, keeping quiescent current independent of output transistor temperature. Distortion was reduced to the desired level without sacrificing stability, and reliability was improved. This arrangement went on to win a Design Council award in 1969.
This power amplifier’s superlative build quality, plus the huge numbers sold (nearly 100,000 units were made), mean it is still readily available today secondhand. Furthermore, it responds extremely well to a service – Quad’s own overhaul package sees a number of passive components, including all the big capacitors, being replaced, and NET Audio has made an excellent name for itself over the past decade refurbishing 33s and 303s, too. Realistically, £250 will have a 303 returned to rude health with large amounts of better toleranced modern components installed, sounding finer than ever.
The Quad offers a solid 45W RMS per channel of power, which was a huge amount at the time of its launch, but it’s important to note than loudspeakers at that time were of fairly high impedance. The 303 doesn’t like driving things rated much less than 8 ohms. Purists often run two 303s per channel with bi-wirable loudspeakers, and this ‘dual mono’ configuration really ups the performance. Properly matched to a sensible speaker, the Quad sounds very smooth and svelte, comfortably powerful, lucidly musical and surprisingly detailed. It’s a far more modern sound than its age suggests, although you don’t quite get the forensic treble and seismic bass of the Quad 909, for example.
There was a time when you could pick up a well used 303 for £50, but prices are creeping up towards £200 for one in good cosmetic condition. The matching 33 preamp is the traditional sonic and aesthetic match for the power amp, but 303s made from 1982 were of course sold with the 34 preamplifier, which is a better overall design – not least because of its replaceable input module cards for MC cartridges and CD players. Properly refurbished, matched and set-up, Quad’s 303 is a great British amplifier and remains one of the finest classic amplifier bargains around. How long will prices stay so low?